新生豚鼠心肌缺血-再灌注时G蛋白含量的变化

Changes of the Level of G Protein in Newborn Guinea-pig Myocardium Undergoing Global Ischemic Reperfusion

目的 研究新生豚鼠心肌缺血 -再灌注时兴奋性鸟核苷耦联蛋白 α亚基 (Gsα)和抑制性蛋白 α亚基 (Giα)含量的变化以及 St. Thomas 号液和冷血心脏停搏液对这种变化的不同影响。 方法 30只新生豚鼠随机分为 3组 ,建立离体心脏左心做功模型 ,组 (n=10 ) :低温对照 ;组 (n=10 ) :St.Thomas 号液灌注 ;组 (n=10 ) :冷血心脏停搏液灌注。采用 Western印迹杂交法研究 Gsα和 Giα蛋白含量的变化。 结果 缺血前 3组的 Gsα和 Giα蛋白含量差别均无统计学意义。缺血后 ,组 和组 Gsα蛋白水平显著低于缺血前 (P<0 .0 1) ,组 较缺血前无明显降低 (P>0 .0 5 )。再灌注后 ,组 Gsα蛋白与缺血前水平相近 (P>0 .0 5 ) ,且明显高于组 和组 (P<0 .0 1)。缺血后和再灌注后 ,组 的 Giα蛋白含量与缺血前比较差别无统计学意义 (P>0 .0 5 ) ,明显低于组 和组 (P<0 .0 1) ;组 和组 仍明显高于缺血前 (P<0 .0 1)。 结论 新生豚鼠心肌 2 0℃缺血 -再灌注时 Gsα蛋白含量明显降低 ,而 Giα蛋白含量显著升高。 St. Thomas 号液不能改变这种变化 ,而冷血心脏停搏液可使新生豚鼠心肌再灌注后的 Gsα和 Giα蛋白含量恢复至缺血前水平。Gsα和 Giα蛋白的平衡遭受破坏可能是未成熟心肌缺血 -再灌注损伤发生?

Objective To study the changes of levels of a subunits of stimulatory （Gsα） and inhibitory guanine nucleotide binding protein （Giα） in newborn guinea-pig （0 2 days old） myocardium undergoing global ischemic reperfusion, and influences on the changes by St. Thomas Ⅱ and cold blood cardioplegic solution. Methods Thirty newborn guinea-pigs were randomly assigned to three groups. Group Ⅰ （n= 10）： the newborn hearts suffered by hypothermic global ischemia; group Ⅱ （n=10）： the newborn hearts arrested by St. Thomas Ⅱ , and group Ⅲ （n= 10） ： the newborn hearts arrested by cold blood cardioplegic solution. Levels of Gsα and Giα were investigated with Western blot analysis. Results No differences of levels of Gsa and Gia were found in three groups before ischemia （P〉0.05）. The level of Gsa after ischemia was significantly decreased than before ischemia in group I and group （P〈0.01）, whereas no pronounced changes in group Ⅲ （P〉0.05） were noted after ischemia. The level of Gsα in group Ⅲ was not significantly changed after reperfusion compared with before ischemia（P〉0.05）, and it was much higher than those in group I and group Ⅱ （P〈0.01）. Level of Giα was found not markedly changed in group Ⅲ after reperfusion compared with that before ischemia, but was notable higher in group Ⅰ and group Ⅱ （P〈0. 01）. Conclusions Significant decrease of level of Gsα, whereas marked increase of level of Giα are found in myocardium of newborn guinea-pig undergoing hypothermic （20 C ） ischemic reperfusion. No impact of St. Thomas Ⅲ on these changes is verified, but recovery to the level of Gsα and Giα before ischemia is achieved by cold blood cardioplegic solution after ischemia and reperfusion. Unbalance between Gsα and Giαis the one of the mechanisms of ischemic reperfusion injury for immature myocardium.